In the past, gyroscopes and gyroscopic devices were constructed of relatively large and expensive electromagnetic devices. These electromagnetic devices incorporated coils and position sensors mounted for relatively high speed, continuous rotational movement. Eventually, micromechanical rate gyros were developed which included components formed by semiconductor processing techniques.
Generally, the micromechanical rate gyros are constructed with a suspended proof mass. The proof mass can be mounted in a gimbal structure including mutually orthogonal flexible axes, with the mass and gimbal structure generally lying in a common plane. The proof mass and inner mounting gimbal can be oscillated or vibrated about a first of the orthogonal axes. Movement, such as rotational movement about an axis perpendicular to the common plane can produce vibrational movement about the other of the orthogonal axes. The deflections are caused by a combination of movement of the vibrating proof mass and resulting Coriolis forces. Robust performance of a gyroscope sensor can depend on the sensing and stability of the proof mass oscillations.